Method of producing a thick-walled seamless metallic tube



Dec. 2, 1941. s, EcK 2,264,455

METHOD OF PRODUCING A THICK-WALLED SEAMLESS METALLIC TUBE filed Aug. '7, 1939 fizz/022107? 57"EI/EN P PEcK,

. le'ss tubes such as drill rods or the like.

Patented Dec. 2, 1941 METHOD OF PRODUCING A THICK-WALLE SEAMLESS METALLIC TUBE Steven P. Peck, Ellwood City, Pa., assignor to National Tube Company,

Jersey a corporation of New Application August 7, 1939, Serial N... 288,876

1 Claim.

This invention relates to thick-walled seam- A drill rod is a tube having an outside diameter of approximately 1.25 inches and an inside diameter of approximately .25 inch to .375 inch. Solid rods are not used as water orother drilling fluid is pumped through the inside of the rod and forces the loosened material up around the rod and out of the hole. Due to the hard usage to which drill rods are subjected, it is essential that the bore be concentric and smooth, as folds, seams or laps will result in cracking and fatigue failure due to the sharp repeated shocks transmitted to the bit through the drill rod by means of an air gun.

The conventional manufacture of drill rods is to cast a solid ingot, drill a hole therethrough, place a mandrel in the bore, and reduce the ingot to proper dimensions, generally by forging. This is a costly process.

Itis among the objects of the present invention to produce a drill rod in a very economical manner.

The foregoing and other objects will be apparent after referring to the drawing, in which:

Figure 1 is a plan of a piercing mill which is adapted to transform a heated solid billet into a tubular blank;

Figure 2 is a sectional elevation of a highmill" or plug-mill which is constructed and arranged to reduce the diameter of a tubular blank and also its wall thickness;

Figure 3 is a plan of a reeling mill which is adapted to smooth the interior and exterior surfaces of a tubular blank;

Figure 4 is an elevation of a sinkingv mill which is adapted to reduce the diameter of the tubular blank and also increase its wall thickness; and

Figure 5 is an end elevation of a sizing mill which is adapted to reduce the outside diameter of a tubular blank,to the desired size.

The process of the invention comprises manufacturing drill rod by the seamless tube method and includes theheating of" a round steel billet or bar, piercing, rolling, reeling and sinking the same and after the production of a proper tube billet it is cold drawn in order to round up the 'inside which tends to get .badly out of round during the heavy sinking operations. That is to say, the individual steps comprising the seamless tube method (heating of a round steel billet or bar, piercing, rolling, reeling and sinking the same) are conventional; but not in the manuof opposed grooved rolls l2 which are altemafacture of drill rods which, as stated hereinbefore, is to cast a solid ingot, drill a hole there-v through, place within the bore a mandrel, and reduce the ingot to proper dimensions, generally by forging. Subsequent to the cold-drawing step the tubes are subjected to a further hot sinking operation to reduce them to size and to obtain a structural condition in the metal most resistant to fatigue This process permits the production of a drill rod having unusual properties imparted to it by the various steps of processing which add to the strength, toughness and fatigue resisting properties of the steel.

As a specific example of the above process, ingots were reduced to3 A inch rounds which were pierced, rolled, reeled and reduced to hollow billets of 1.660 inches 0. D. by .420 inch wall. These hot rolled tubes were given one cold draw pass reducing them to 1.531 inches 0. D. x .410 inch wall. Following'this, the cold draw tubes were sunk to 1% inches 0. D. by .469 inch wall in a sinking mill.

Referring more particularly to the drawing,

thev numeral 2 designates a pair of power driven metal-working rolls of the "Mannesmann or barrel type between which is disposed a suitable piercing point 3. In the manner well understood in the. art, a solid highly-heated billet A is fed between the metal-working rolls 2 and over the piercing point 3, whereby there is obtained a tubular blank B.

,Referringto Figure 2, the numeral 5 designates a pair of superimposed grooved metalworking rolls which comprise. a high-mill or plug -mill, and upon which there is disposed a plug or bar 6. In utilizing this type of mill the tubular blank B is introduced between the rolls 5 and over the plug or bar 6,-whereupon its interior and exterior diameters are substantially changed, as shown atC, without very material change in the wall thickness.

The reeling mill of Figure 3 comprises a pair of rolls 8 of the Mannesmann or barrel type between which there is disposed a plug or bar 9. In the operation of this mill a tubular blank, designated at C, is drawn between the rolls ;8 and over the plug or bar 9, whereupon the interior and exterior surfaces of the tubular workpiece C are smoothed out, thereby providing a workpiece D having these improved characteristics.

The sinking mill of Figure 4 comprises a series *tively disposed at normal angles with respect to the piercing point. This type of mill does not employ a mandrel for disposition interlorly of tie blank, as the mill is adapted to reduce the interior and exterior diameters of the tubular blank with an accompanying increase in wall thickness.

The sizing mill of Figure 5 comprises at least one pair of superimposed grooved rolls H, but no intermediately disposed mandrel whereby the rolls [4 are adapted to reduce the outside diameter of the tubular blank, together with a slight reduction in the inside diameter thereof, accompanied possibly by a very slight increase in the wall thickness.

It will be understood that while the method of the present invention is particularly designed for producing thick-walled seamless tubes such as are used for drill rods, it may be utilized for producing thick-walled seamless tubes for any purpose desired.

While I have shown and described several specific embodiments of the present invention, it will be seen that I do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of the invention, as defined by the following claim.

I claim:

The method of producing a thick-walled seamless metallic tube which comprises piercing a heated solid billet by helically rolling to thereby obtain a seamless tube, permitting the seamless tube to cool to a cold-working temperature, colddrawing the seamless tube over a mandrel to materially reduce eccentricities of the bore, and hot-sinking the seamless tube to the desired inner diameter.

STEVEN P. PE CK. 

